1. Field of the Invention
The invention relates to devices for disposing a blade (i.e., blade holder) near a device for transporting a continuous web of material, such as a roll or a drying cylinder of a paper machine, wherein the blade is held in a blade clamping device which can be brought to a position transverse to a direction of movement of the continuous material. In particular, the invention relates to such a device wherein a blade clamping device is disposed on a blade supporting beam, extending transversely to the direction of movement of the web, and a supporting element is coupled with a first drag bearing on a stand and with a second drag bearing on the blade supporting beam.
2. Description of Related Technology
A blade disposed near a continuous web transport device may be used, for example, for the coating of a paper web with a coating composition wherein the blade is utilized to produce a layer of coating having a thickness which is as uniform as possible. Another possible application is the use in the production of crepe paper in which a continuous material runs onto a doctor arranged on a transport roll in order to produce the structure which is typical for crepe paper. In both applications, the paper quality is influenced by the pressing pressure of the blade on the continuous web of material or on the transport device as well as by the size of the working angle of the blade.
Therefore, in order to produce a good working result, it is necessary to be able to bring a blade into a predetermined position with respect to a transport device as precisely possible. However, blades wear and therefore, after they reach their wear limit, they must be replaced or reground. In order to carry out such maintenance, the blade is usually removed from it working position at the roll. In order to be able to produce uniform high quality paper products, it is necessary that the blade of the doctor or scraper be brought exactly to the previously occupied working position. Similarly, blades should be displaceable in their working position, for example, in order to optimize paper quality or in order to reset the paper machine to another type of paper. However, it has been difficult to adjust predetermined blade positions with good repeatable accuracy. Thus, blade holders have been utilized to provide such adjustments.
A blade holder disclosed in EP Patent 0 137 837 shows the arrangement of a blade of a doctor achieved through two rotary movements of a blade supporting beam around a swiveling or rotating axis which is perpendicular to a direction of transport of a web of material through the device. In order to change the position of the blade on the roll, the blade holder has two actuating drives with threaded drives that can be coupled to one another with a coupling and a bevel gear pair. With such a blade holder (which is structurally relatively expensive), although the pressing pressure and the working angle of the blade can be varied independently of one another, it is an unsatisfactory aspect that, after changing or grinding of the blade, for which purpose the blade supporting beam is swung away from the roll, the working angle of the blade must be adjusted again in a relatively complicated way, i.e., "manually", when the new or reground blade is brought to the roll. In order to avoid impairment of quality, this must be done very accurately. However, precise adjustment of this angle is time-consuming and therefore costly.